Safety device for burners



April 30, 1929. N. r. sELLMAN l SAFETY DEVICE FOR BURNERS Filed Nov. 1'2, 1927 2 Sheets-Sheet l April 30, 1929. N, r SELLMAN 1,711,398

SAFETY DEVICE Fon BURNERS Filed Nov. 12, 1927 2 Sheets-Sheet 2 jzvenzo 7a was if ,mf/

. cally 45 drawings showing -recommended Patented Apr. 30,1929.

UNITED STATES NILs 'i'. snLLMAN, or NEW Yoan, cnn THERMOSTAT' COMPANY,

N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, T0 SEEN'- QF CAMBRIDGE, MASSAGEUSETTS, A. CORPORATION y 0F MASSACHUSETTS, i SAFETY DEVICE FOR BUBNERS.

`Application led Novemberl, 1927. Serial No; 232,875. i

This invention relates to gas burners, and more particularly Ato automatic devices `operable upon accidental eX- tinguishment of the burner iiame to shut 0H the gas supplyof Buiisenburners vor pilot lights such as are commonly associated wit water heaters, boilers, .stoves and other gas heating appliances. A principal object of the .invention is to provide a thermostaticontrolled device which will stop. the flowof gasto thel burner or pilot when `the flame is extinguished, `yet which will not normally interfere with a free supply of gas and will not cause faulty combustion or a flame of poor quality. y

Although the pr'vision of a thermostatic ycontrol within the tube of a gas lighter having a Yiiame spreading jet has heretofore d head of the needle valve to obviate the posbeen suggested, such a construction woul not satisfy the purposes of this invention, for the interposition oftflow-retarding element in the gas passage of a burner operating at low pressure results in poor combustion and a feeble or unsatisfactory fiame. In a Bunsen burner, particularly,.the consequent resistance to the freeow of the gas and air mixture would cause a'yellow flame instead of the desired and characteristic blue lia'me of this type of burner. Another undesirable result of such a disposition of the thermostat is that ajlame after a fiashs back would hold the thermostatic device at high temper-ature so that the gas supply would not be shut off. .f Furthermore, such be cleaned successfully a burner can not without detaching the thermostatic control or disturbing its adjustment.

A .particularfeature ofthe present invention accordingly resides in the provision of a thermostat associated with the exterior of the burner tube, and operated by the changes in temperatureof the tuberather thanby the temperature ofthe flame. .This feature is illustrated in ments of thel invention as appliedfto al pilot ,burner adapted for use in gas refrigeration systems, or fo-r. similar purposes. Y

In the "drawings: Y.

Fig. lis an elevation of a burner equipped with the improved safety' device; s

Fig. 2 is'asection on the line 2--2 of Fig: 1, :with portions of the apparatus in side elevation safety devices for .mounted within ,the casing with its the accompai'iying` embodi' Si@ 4disk 20 will not be so ytightly gripped beits efficient operation,

I Fig. 3 isa plan view of the structure illusy trated in Fig. 2;v

. Figs. 4 and 5 are views similar to Figs. 1 an 2 showing a modified construction of safety device; and c Fig. 6 is a'plan view of a metal blank suitable for .the formation of a heat conduct-ing element included in the modified structure.

The burner may be ,of any suitable coii'- struction, preferably of the Bunsen type as shown, and cpmprises gas inlet 4 connected to'a supply pipe .5 l and terminating at an orifice 6, a mixing chamber 7 having air ports 8 and an outer rotatable air adjusting sleeve 9, and a-burner tube 10. A needle valve 11 may be provided for 4the orifice 6 and a cap 12 may be threaded upon an annular shoulder of the inlet pipe over the screw sibility of as leaka e.` As showi? g a shoulder 13 spaced a short distance laterally from the top to the burner tube 10, and within the shoulder is formed an aperture 14 about whichis a valve seat with which a valve 15 cooperates to control the passage of gas into the inlet. Between the shoulder 13 and the tube 1() is mounted a casing consisting of a cup ed member 16, havi a nipple threaded into the inlet ipe, an a second hemispherical member 1 having a peripheral kiange crimped over the outer edge of the member 16. The crown of the in Fig. 2 the 'inlet pipe 4 has member 17 is` cut awa at 18 to receive a por- I tion of the burner tu e 10 within the casing.

If desired a spring cli 19 ma be provided tolfold the burner tig tly wit n the casing recess, but ordinarily the dimensions of the elements will be such that the casin is supp the tube without a dition'al ported close toI binding means. A thermostaticdisk 20 is peripheryreceived between the edge portions of members 16 and 17 and is connected by a.

m 21 to the valve 15. In order'that the tween the members 16 an a spacer ring 21, which should be slightly (e. .005 inch) thicker than the disk, is pre erably provided between said members. The inner diameter of the ring v21 may be slightly' greaterthan .100'. 17 as to prevent the diameter of thedisk 20, asindicatedl in the drawing, to prevent'binding.

p soldering, bra-zing,

The disk 20 is preferably bi-metallic, be-

ing formed of two component disks welded together, the materials such as iron and `brass of the respective disks having diferent coeilicients of expansion. The sk 20 is normally cupped (as by swaging) in such direction that the component part having the higher coeicient of expansion is on the concave side. Consequently upon raising the temperature of the disk the unequal expansion of the materials formin the disk will cause a tendency to flatten t e cupped surface until at a predetermined tem erature a .sudden curving in the opposite irection occurs, which reversal of shape will be maintained until the temperature has been Substantially lowered; Thereafter upon reaching a substantially lower temperature, the disk wiill suddenly return to its initial shape. The materals andthickness of the component parts and the degree of curvature are so chosen that the disk will snap in one direction when heated to the desired tempera-l ture (e.'g.'120 F.) and will snap back at a lower temperature (e. g. 100"` F.). Suitable 'materials are sheet brass and nickel steel having a thickness of .005 and .005 inches respectively and suitable cupping. for a disk 1% inch in diameter is .02 inches.

It will be understood however that the present invention is not limited to any particular combination of materials having different thermal coeilicients of expansion but is intended to embrace in its scope any combination of materials having dissimilar thermal coeilicients of expansion suflicient to cause the reversal of curvature. Furthermore, the two materials comprising the composite thermostatic disk may be secured together in any desired manner by riveting, or otherwise although it is preferred to unite the materials comprising the disk by welding or similar means to secure a substantially indivisible she t.

When the gas burner is lighted as shown in Fig. 2, the heat of the flame is transmitted to the wall f the burner tube 10 and thence into vthe casing and to the thermostatic disk 2O which, as shown, assumes a curve awa from the burner tube 10 and thus holds the valve 15 off. seat, allowin gas to flow through the inlet ipe 4. s soon as the fiame is extinguisiied either intentionally or accidentally the` burnerI tube 10 will be cooled substantially to room -item erature and the consequentreaction upon t e thermostati'c disk 2O will cause the same to snap abruptly to the left of Fig. 2 closing the valve 15 and thereby shutting off the gas supply. When itis desired to relight the burner, the heat from the Hameof a match held beneath thel casing' will change the shape of the disk to open the valve. The change abrupt whether in one direction o r the other,

as freely as an ordinaryv .ing a shoulder spaced a short of shape inthe disk is decidedly,

so that the valve is seated or unseated according to the temperature of the disk 20 which is constructed in such la manner that changes in shape occur withv considerable force, so that positive closing and opening of the gas passage is insured. Owing to the inherent resiliency and rugged construction of the disk, it will operate indefinitely in a reliable and eiiicient manner.

In the modified construction illustratedin Figs. 4to 6, theY casing for the thermostatic control comprises a cuppedmember 22 fastened to the inlet pipeand having a peripheral ange 23, and a solid dished member 24 fitting within said fiance with its outer surface spaced from the burner tube 25. Aspacer ring 26 fits between the peripheral edgebf the member 24 and the inner surface of member 22 and a thermostatic disk 27 is mounted in the casing withing the spacer ring in substantially the same manner as in Fig. 2. Dispo'sed between the margin of the disk 24 and the peripheral li of the clampin ange 23, is a ring 28 o? metal having Iiigh heat conductivity, which is provided with a conductor stri 29 leading above the burner tube and pre erably having a winged tab 30 disposed around the flame of the burner. TheV ring 28 and its conductor strip may conveniently be formed from a metal blank stamped out as indicated in Fig. 6. The strip 29 and its tab may readily be bent into the form shown in Figs. 4 and 5 before the ring is aiiixed to the casing. In this type of. structure the heat of the burner ame is transmitted to the casing and to the thermostatic disk 27 by the conductor strip 29; otherwise, the operation of the modied device is the same as above described, the construction of the inlet pipe, control valve and burner beil substantially the same as in Figs. l to 3.

The combination of a thermostatic safety device constructed substantially as above described with a gas burner ensures an a upt and positive closing of the gas inlet upon the extinguishment of the flame, and the positioning of the thermostat exterior of the burner tube not only affords an uninterrupted passage through the tube, and allows the burner to be cleaned or adjusted burner, but also permits the thermostat to be enclosed within a casing which protects Vit from injury from flame, soot or other causes.

I claim:

1. In combination with a Bunsen burner havinga burner tube and a sup ly pip'e havistapce from the outer .wall of said tube adjacent its mouth, a valve in said shoulder adapted to shut off the gas supply when seated, a casing supported on said shoulder between the supply pipe and the burner tube, said casing havlng an opening the edge of which contacts with said outer Wall permitting the transfer of heat from the tube into the' casing, and a thermostatic device Within said casing and connected to said Valve, constructed and arranged to hold the valve open when the burner is lighted and abruptly to seat the valve when the flame is extinguished.

2. In combination with a Bunsen burner having a burner tube and a supplypipe having a shoulder spaced a short distance from the outer Wall of 'said tube adjacent its mouth, a Valve in said shoulder adapted to shut o the gas supply when seated, a casing supported on said shoulder between the supply pipe and the burner pipe, said casing having an opening the edge of Which contacts with said outer Wall permitting the transfer of heat from the tube into the casing, and a thermostatic snap acting disk within said casing and connected to said valve, constructed and arranged to hold the valve open when the burner is lighted and abruptly to seat the valve when the flame is extinguished.

3. In combination with a Bunsen burner having a burner tube and a supply pipe having a shoulder spaced a short distance from the outer Wall of said tube adjacent its mouth, a valve in said shoulder adapted to shut off the gas. supply when seated, a. casing supported on said shoulder between the supply pipe' and the burner tube, said casing hay-lng an opening the edge of which contactsltvith said outer wall permitting the transfer of heat from the tube into the casing, a bimetallic disk Within said casing and connected to said valve, constructed and arranged to hold the valve open When the burner is lighted and abruptly to seat the valve when the flame isr extinguished, said disk being mounted within said casing at its periphery.

Signed by me at New York city, N. Y., this twenty-seventh day of October, 1927.

" NILS T. SELLMAN. 

